How much air pressure in tubes for street driving? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ratrod67 · 10-30-2011, 09:45 AM

Any idea how much air pressure I should run in the tubes in my Mickey Thompson 33x19.50 tires? Will be making a 4 hour trip on the freeway real soon. Don't want any issues with these big tires. Thanks.

Marv D · 10-30-2011, 10:58 AM

First,, are they the MT (hard as a rock) Sportsmans?? Or the ET Streets?? The two act very different on the street a nd respond to air pressure very differently. The sportsmans have such a hard sidewall I think you can run them flat on a pickup!!! Seriously,,

In my Hoosiers, and on the street (33x22.50-15 have ran both the treaded QuickTime and the DOT slick QT-pro) 11-14psi seemed to work with tubes on the street, and 9.5 -.10.75 on the TRACK. And stay the hell out of the rain!!!

BUT,, that's with 'MY' low pressure gauge. I checked my slicks at the track one time with a friends gauge and they read almost 3.5 pounds higher. I have an old Tavia I've used forever that is 'consistant' no matter if it's 'right' or not.

Best I can suggest is get a good gauge, and make a few test runs to see what is going to work for you.

ratrod67 · 10-30-2011, 11:44 AM

They are Sportsmans. I am going to be driving the truck about 4 hours one way so I am concerned with heat/expansion and the tube slipping inside the tire. I don't want to wind up with a flat hours from home.

Marv D · 10-30-2011, 01:31 PM

I think the sidewall of the Sportsman says 25psi max to seat the bead??? I'd start at 15 and see how it sits with the weight of the truck. I really don't think you need to worry about temps causing spikes in psi,, maybe if it were too low, but if it sits flat and not cupping in the center.. I bet your fine. One thing to be SURE OF is to get the air out of the 'tire'. I had a new slick / tube go down at the track and thought I had pinched the tube. Put the car i the trailer and went home. When I pulled it apart there was no leak in the tube at all. The tire was sealing against the bead, and with the screw down tube stem it was sealed well enough that the tire was compressing the air OUTSIDE the tube and inflating the tire. The rim screws, or poor seal at the stem allowed it to slowly leak out.

As a habit I air the tire up to seat the bead, release all the air to allow the tube to 'relax' and hopefully unfold any overlaps. Then repeat. In that process I sealed the beads and apparently it sucked air 'in' past the stem, but when inflating it sealed. I have no other explaination other than it did it AGAIN when I put the tire back together. Unloaded the car and tire was low. Said screw it and filled it, it was a little low later in the day,, filled it again and it's held normal small pre-race changes for months. It sure puzzeled me!

dbmx66 · 10-30-2011, 06:14 PM

i have 33x19.50 sportsman on 15x15 rims i run 15 psi (not on track)

68 C-10 KID · 10-30-2011, 09:28 PM

The Tire will gain all most 3 psi on a road trip. I normally set mine at 15-16 cold. I found the softer they are the more they like to track the rut. Then it might be the spool helping out on that also

BigDan3131 · 10-31-2011, 06:21 AM

If you end up removing all the rubber faster than normal

my friend uses Hoosier dirt track tires on his street ride. He said they are cheaper than the MT's and just as hard.

Street Smart · 10-31-2011, 08:40 PM

Quote:

Originally Posted by Marv D

I think the sidewall of the Sportsman says 25psi max to seat the bead??? I'd start at 15 and see how it sits with the weight of the truck. I really don't think you need to worry about temps causing spikes in psi,, maybe if it were too low, but if it sits flat and not cupping in the center.. I bet your fine. One thing to be SURE OF is to get the air out of the 'tire'. I had a new slick / tube go down at the track and thought I had pinched the tube. Put the car i the trailer and went home. When I pulled it apart there was no leak in the tube at all. The tire was sealing against the bead, and with the screw down tube stem it was sealed well enough that the tire was compressing the air OUTSIDE the tube and inflating the tire. The rim screws, or poor seal at the stem allowed it to slowly leak out.

As a habit I air the tire up to seat the bead, release all the air to allow the tube to 'relax' and hopefully unfold any overlaps. Then repeat. In that process I sealed the beads and apparently it sucked air 'in' past the stem, but when inflating it sealed. I have no other explaination other than it did it AGAIN when I put the tire back together. Unloaded the car and tire was low. Said screw it and filled it, it was a little low later in the day,, filled it again and it's held normal small pre-race changes for months. It sure puzzeled me!

great advice, i always seat the tire then relax the tube. i had a crazy vibration years ago from a folded or twisted tube, deflated then refilled then it was good. I know guys that sprinkle baby powder in the tire too, helps the tube get in place.

nxtruck · 11-01-2011, 10:18 AM

X2 on using baby powder inbetween the tire and the tube. Lets things slide around rather than getting pinched and stuck.

prostreetC-10 · 11-05-2011, 10:24 PM

Are they sportsman or sportsman pro? Why are you running tubes? I can't remember if the sidewalls say tubes or not but I talked with M/T and they said they are fine without tubes. I'm running 29x18.5s on 15x14s tubeless with about 16 psi. It sits for about 9 months a year and never a problem. The tubes will cause the whole setup to run hotter than the tubeless way. Have fun on your trip. These tires acutally suck in my opinion. I just run around town and that's it. Can't wait to get them off for the S/R radials or Hoosiers. I've talked to many guys that have gone from the fatty bias to radials and everyone says you won't believe the diff!!

Drive safe!

68 C-10 KID · 11-06-2011, 01:20 AM

Quote:

Originally Posted by prostreetC-10

Are they sportsman or sportsman pro? Why are you running tubes? I can't remember if the sidewalls say tubes or not but I talked with M/T and they said they are fine without tubes. I'm running 29x18.5s on 15x14s tubeless with about 16 psi. It sits for about 9 months a year and never a problem. The tubes will cause the whole setup to run hotter than the tubeless way. Have fun on your trip. These tires acutally suck in my opinion. I just run around town and that's it. Can't wait to get them off for the S/R radials or Hoosiers. I've talked to many guys that have gone from the fatty bias to radials and everyone says you won't believe the diff!!

Drive safe!

That's what I wanted to hear about switching over to a big radials.

Thanks

prostreetC-10 · 11-06-2011, 10:04 AM

I think the only reason why guys even run the bias ply meats in the first place is because of cost. Those radials are spendy! I bought my 18.5s WITH M/T "natural rubber" tubes for $100. I sold the tubes alone on eBay for $100 so the tires were free. One of my best deals ever. I go over a set a railroad track and that ass end takes a block to recover. We have a lot of snow out here and the roads get grooved with snudded tires since we don't use salt. You get those fatties hung up in those grooves in the summer and you better hold on. It will pitch you all over the place. It's like trying to take a school bus through a pro-touring course!!! lol

10-30-2011, 09:45 AM	#1
ratrod67 Registered User Join Date: Sep 2002 Location: DFW Texas Posts: 2,270	How much air pressure in tubes for street driving? Any idea how much air pressure I should run in the tubes in my Mickey Thompson 33x19.50 tires? Will be making a 4 hour trip on the freeway real soon. Don't want any issues with these big tires. Thanks.

10-30-2011, 10:58 AM	#2
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: How much air pressure in tubes for street driving? First,, are they the MT (hard as a rock) Sportsmans?? Or the ET Streets?? The two act very different on the street a nd respond to air pressure very differently. The sportsmans have such a hard sidewall I think you can run them flat on a pickup!!! Seriously,, In my Hoosiers, and on the street (33x22.50-15 have ran both the treaded QuickTime and the DOT slick QT-pro) 11-14psi seemed to work with tubes on the street, and 9.5 -.10.75 on the TRACK. And stay the hell out of the rain!!! BUT,, that's with 'MY' low pressure gauge. I checked my slicks at the track one time with a friends gauge and they read almost 3.5 pounds higher. I have an old Tavia I've used forever that is 'consistant' no matter if it's 'right' or not. Best I can suggest is get a good gauge, and make a few test runs to see what is going to work for you. __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.

10-30-2011, 11:44 AM	#3
ratrod67 Registered User Join Date: Sep 2002 Location: DFW Texas Posts: 2,270	Re: How much air pressure in tubes for street driving? They are Sportsmans. I am going to be driving the truck about 4 hours one way so I am concerned with heat/expansion and the tube slipping inside the tire. I don't want to wind up with a flat hours from home.

10-30-2011, 01:31 PM	#4
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: How much air pressure in tubes for street driving? I think the sidewall of the Sportsman says 25psi max to seat the bead??? I'd start at 15 and see how it sits with the weight of the truck. I really don't think you need to worry about temps causing spikes in psi,, maybe if it were too low, but if it sits flat and not cupping in the center.. I bet your fine. One thing to be SURE OF is to get the air out of the 'tire'. I had a new slick / tube go down at the track and thought I had pinched the tube. Put the car i the trailer and went home. When I pulled it apart there was no leak in the tube at all. The tire was sealing against the bead, and with the screw down tube stem it was sealed well enough that the tire was compressing the air OUTSIDE the tube and inflating the tire. The rim screws, or poor seal at the stem allowed it to slowly leak out. As a habit I air the tire up to seat the bead, release all the air to allow the tube to 'relax' and hopefully unfold any overlaps. Then repeat. In that process I sealed the beads and apparently it sucked air 'in' past the stem, but when inflating it sealed. I have no other explaination other than it did it AGAIN when I put the tire back together. Unloaded the car and tire was low. Said screw it and filled it, it was a little low later in the day,, filled it again and it's held normal small pre-race changes for months. It sure puzzeled me! __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.

10-30-2011, 06:14 PM	#5
dbmx66 Registered User Join Date: Aug 2009 Location: PA Posts: 883	Re: How much air pressure in tubes for street driving? i have 33x19.50 sportsman on 15x15 rims i run 15 psi (not on track)

10-30-2011, 09:28 PM	#6
68 C-10 KID Mean Green Join Date: Sep 2007 Location: Portland, OR Posts: 522	Re: How much air pressure in tubes for street driving? The Tire will gain all most 3 psi on a road trip. I normally set mine at 15-16 cold. I found the softer they are the more they like to track the rut. Then it might be the spool helping out on that also __________________ 427 SBC 683HP & 590ftlbsTRQ @ fly wheel. 60'-1.38 1/4-10.43 MPH-124.6 New ET current 4/2019 AKA MEAN GREEN.

10-31-2011, 06:21 AM	#7
BigDan3131 Registered User Join Date: Jun 2006 Location: Maple Valley, WA Posts: 1,913	Re: How much air pressure in tubes for street driving? If you end up removing all the rubber faster than normal my friend uses Hoosier dirt track tires on his street ride. He said they are cheaper than the MT's and just as hard.

11-01-2011, 10:18 AM	#9
nxtruck Registered User Join Date: Jun 2006 Location: Jackson, Mo. Posts: 607	Re: How much air pressure in tubes for street driving? X2 on using baby powder inbetween the tire and the tube. Lets things slide around rather than getting pinched and stuck. __________________ Chris 1966 Chevy C10 LWB, 434 sbc, TH350, 12-bolt, factory suspension, pump gas 7.02 @ 95.8, 1.45 60' 1965 Chevy C10 LWB, 355 sbc, TH350, daily driver

11-05-2011, 10:24 PM	#10
prostreetC-10 My Carbon Footprint Join Date: Oct 2008 Location: Orygun Posts: 5,527	Re: How much air pressure in tubes for street driving? Are they sportsman or sportsman pro? Why are you running tubes? I can't remember if the sidewalls say tubes or not but I talked with M/T and they said they are fine without tubes. I'm running 29x18.5s on 15x14s tubeless with about 16 psi. It sits for about 9 months a year and never a problem. The tubes will cause the whole setup to run hotter than the tubeless way. Have fun on your trip. These tires acutally suck in my opinion. I just run around town and that's it. Can't wait to get them off for the S/R radials or Hoosiers. I've talked to many guys that have gone from the fatty bias to radials and everyone says you won't believe the diff!! Drive safe! __________________ A quick "pedalfest" *Still getting loose (carb test)* 496 Initial fire up video!

11-06-2011, 10:04 AM	#12
prostreetC-10 My Carbon Footprint Join Date: Oct 2008 Location: Orygun Posts: 5,527	Re: How much air pressure in tubes for street driving? I think the only reason why guys even run the bias ply meats in the first place is because of cost. Those radials are spendy! I bought my 18.5s WITH M/T "natural rubber" tubes for $100. I sold the tubes alone on eBay for $100 so the tires were free. One of my best deals ever. I go over a set a railroad track and that ass end takes a block to recover. We have a lot of snow out here and the roads get grooved with snudded tires since we don't use salt. You get those fatties hung up in those grooves in the summer and you better hold on. It will pitch you all over the place. It's like trying to take a school bus through a pro-touring course!!! lol __________________ A quick "pedalfest" *Still getting loose (carb test)* 496 Initial fire up video!



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